German Pat. DE-PS No. 29 19 209 discloses a system for raising either a print or a correction ribbon via cams driven by a single bidirectional motor, the direction of motor rotation determining which ribbon will be raised. In this system, however, the print ribbon is lowered to its normal position after each print action as is necessary in typewriters to clear the view of the typing line. In memory controlled printer operation when the rate of printing is higher, this would be disadvantageous because it limits the rate of printing. Moreover, the noted German patent says nothing regarding ribbon transport.
Copending U.S. application, Ser. No. 571,451 filed Jan. 17, 1984 also shows a single motor for powering different types of ribbon, in, e.g., a printer. This application does not mention correction ribbons.
U.S. Pat. No. 4,407,594 relates to a drive system having a motor for raising and transporting a print ribbon but only for raising a correction ribbon. The correction ribbon transport is powered by a Bowden wire connection to an electromagnet which is also operative to switch drive connections between print and correction modes. Here, too, the print ribbon returns to lowered position after each print action and is therefore ill suited to use in high speed printer operation.